More than 10 years after the release of Golden Rice – rice genetically modified to contain high levels of provitamin A – trials are about to begin in Bangladesh and the Philippines to assess whether eating Golden Rice really does increase vitamin A levels in the body. Vitamin A deficiency is a cause of blindness in many parts of the world where malnutrition is a problem and is also associated with other health problems.
So why has it taken so long? Had it been produced by ‘conventional’ breeding, Golden Rice would almost certainly have been available years ago. Regulations governing the acceptance of genetically engineered crops and a host of IP issues have delayed or prevented its introduction. Newer strains of Golden Rice bred in the last few years have even higher levels of the provitamin A (beta-carotene) which gives it its characteristic ‘golden’ colour, and one bowl a day of this rice could provide the entire dietary requirement of the nutrient.
The emphasis is on the word ‘could’ and this is why participation of the Helen Keller Foundation in a new IRRI (International Rice Research Institute) project is pivotal. I hadn't realized that, whilst Golden Rice grains are high in provitamin A, it’s still unclear whether this results in long-term increases in vitamin A in the body. Clinical studies in 20091 in which Golden Rice was served to a sample of healthy adult volunteers concluded that beta-carotene derived from Golden Rice did effectively convert to vitamin A in humans, but the sample was small and the study short-term.
The trials in Bangladesh and the Philippines should help determine whether daily consumption of Golden Rice can help reduce vitamin A deficiency on an ongoing basis and hence reduce blindness. The project will also generate and collect safety information related to Golden Rice for submission to regulators in 2013 in the Philippines and 2015 in Bangladesh. Golden Rice is expected to cost farmers about the same
as other rice, and they will be able to save seeds for replanting.
CAB Abstracts covers all aspects of breeding and development of “Golden Rice” and its potential for solving malnutrition due to vitamin A deficiency, with over 100 abstracts of research ranging from genetic engineering to biosafety and food security.
1. Tang, G. W.; Qin, J.; Dolnikowski, G. G.; Russell, R. M.; Grusak, M. A. Golden Rice is an effective source of vitamin A. American Journal of Clinical Nutrition, 2009, 89, 6, pp 1776-1783, 29 ref.
The creation of transgenic plants often involves the use of DNA sequences from bacteria and other non-plant organisms – in particular as vectors to introduce the desired genes. However, some people are concerned about the use of DNA from such distantly related sources, and regulators require separate rules to be complied with for transgenic plants compared to those derived by selective breeding. Could using plant-derived sequences help address those fears and reduce the regulatory burden for crop biotechnologists?
Tony Conner and his colleagues from Plant and Food Research, New Zealand consider the potential for intragenic vectors in a paper in CAB Reviews. This involves finding DNA fragments within a plant species that are very similar to those from foreign DNA that have been used as vectors for many years. Various techniques have been developed, some involving small amounts of foreign DNA, but fully intragenic plants have no foreign DNA and are entirely composed from plant-derived sequences.
Genetically modified crops containing a toxin gene from the bacterium Bacillus thuringiensis have been used by farmers for 11 years now. These Bt crops were designed to give the plants resistance to important pests. But might they also be harming non-target invertebrates? A study by Steven Naranjo of the US Department of Agriculture’s Agricultural Research Service looks at the evidence and compares it with the impacts of the pesticides that would otherwise have been used.
Bt maize and cotton have been commercially produced on about 42 million hectares in 20 countries. Their potential non-target effects have been considered in over 360 published research papers. Naranjo, in his paper in CAB Reviews, looks across around 200 of these studies to draw conclusions.
Investigations found that the abundance of all non-target invertebrates was slightly lower for Bt crops than in non-Bt crops, but much higher in Bt crops than in non-Bt crops treated with insecticides. Using meta-analysis, a way of doing a meaningful comparison across different studies, Naranjo found that laboratory studies indicated negative effects of Bt on some non-target invertebrates, though these depended on how the trials were done and which invertebrates were being looked at. However, few harmful effects of Bt crops were shown in field studies. One factor may be that exposure to the Bt toxin is higher in the laboratory experiments than in the field. It was also clear that nontarget effects for insecticides are much greater than for Bt crops.
While Bt crops mean that some specialist parasitoids that would otherwise attack pests of maize have less to feed on, the overall levels of predation on pests have not been shown to drop. Naranjo believes Bt crops could enhance the role of biological control in integrated pest management.
Naranjo's paper emphasises that a key comparison to make is what would have happened without Bt crops. Bt maize and Bt cotton are believed to have led to a 136.6 million kg reduction in insecticide active ingredient, and rootworm-resistance crops will reduce the levels of insecticide present in the soil.
The paper, "Impacts of Bt crops on non-target invertebrates and insecticide use patterns" by Steven E. Naranjo appears in CAB Reviews: Perspectives in Agriculture, Veterinary Science, Nutrition and Natural Resources, 2009, 4, No. 011, 23 pp.
Download full CAB Reviews article